Wide-angle objective with negative front component and multilens positive component



350-460 5R 5mm mu OR 39410t6 'F FUT'I f K '4 I O p 4/0 7 Nov. 12, 1968 w. WOLTCHE 3,410,632 WIDE-ANGLE OBJECTIVE WITH NEGATIVE FRONT COMPONENT AND MULTILENS POSITIVE COMPONENT Filed May 24, 1965 5 Sheets-Sheet l r5 r6 r7 r8 r9 r10 r11 Fig.1a

I 2 5 ll k jrz l/emorz' Wa/fer Wb'lfche Attomey WOLTCHE 3,410,632

Nov. 12, 1968 w WIDE-ANGLE OBJECTIVE WITH NEGATIVE FRONT COMPONENT AND MULTILENS POSITIVE COMPONENT 5 Sheets-Sheet 2 Filed May 24, 1965 Fig.2

Inventor: Wa/fer W'o'lfche BY g? Attorney Nov. 12, 1968 w. WOLTCHE 3,410,632 WIDE-ANGLE OBJECTIVE WITH NEGATIVE FRONT COMPONENT AND MULTILENS POSITIVE COMPONENT Filed May 24, 1965 5 Sheets-Sheet 5 Fig.3

I'm/anion Walter Wolfche Attorn Y United States Patent 3,410,632 WIDE-ANGLE OBJECTIVE WITH NEGATIVE FRONT COMPONENT AND MULTILENS POSITIVE COMPONENT Walter Woltche, Bad Kreuznach, Germany, assignor to Jos. Schneider & Co. Optische Werke, Kreuznach, Germany, a corporation of Germany Filed May 24, 1965, Ser. No. 458,189 Claims priority, application Germany, May 30, 1964, Sch 35,253 3 Claims. (Cl. 350-214) ABSTRACT OF THE DISCLOSURE Wide-angle objective with negative front component of l to 3 lens members and positive rear component of four lens members, the second or third lens member of the latter component being a doublet.

My present invention relates to a wide-angle objective for photographic or cinematographic cameras.

In commonly assigned copending application Ser. No. 355,829, filed Mar. 30, 1964 by Rudolph Solisch and me, now Patent No. 3,350,157, there has been disclosed an optical objective of this general type wherein two meniscus-shaped lens members define a diaphragm space by their confronting concave surfaces and are bracketed by two lens groups of positive refractivity. The objective specifically described in that application has an aperture ratio of about 1:1 and a relatively large back-focal length exceeding 50% of the overall focal length of the objective.

In wide-angle objectives of short overall focal-length it is often desirable, for physical as well as optical considerations, to operate with even larger ratios of backfocal length to overall focal length. For purposes of the present description, wide-angle objectives may be defined as those having an angle of view of about 60 or more.

The general object of my invention is to provide a wide-angle objective of the general character set forth wherein the ratio of back-focal length to overall focal length is about 1:1 or greater.

An objective according to my present invention represents, basically, a modification of the objective disclosed in the aforementioned copending application according to which the aforedescribed combination of meniscusshaped members proximal to the diaphragm space and positive members bracketing the menisci is constituted by a positive rear component of a two-component system whose negative front component, consisting of one or more lenses, is separated from this rear component by an air space smaller than the overall focal length of the system, the individual focal length of this negative front component having an absolute value less than twice that of the overall focal length. In contradistinction to the systern of the copending application, the more forwardly disposed meniscus (i.e. the one on the object side of the diaphragm space) may be of either positive or negative refractivity while the associated image-side meniscus, according to a specific feature of this invention, is positively retracting. Both these members should be of relatively low power, with an individual focal length upwards of about twice the overall focal length of the system; in the forward meniscus, whose refractivity is not critical, there is no upper limit for the individual focal length whereas in the rear meniscus this upper limit is-around ten times the overall focal length.

Wide-angle objectives of this construction, with a negative front component of one or more members and a positive rear component consisting of four air-spaced members, have been found to give a very satisfactory op- 3,419,632 Patented Nov. 12, 1968 "ice suant to a further feature of my invention, the radii of the confronting concave meniscus surfaces at the diaphragm space should be so dimensioned that the absolute length of the radius of the object-side meniscus is less than or at most equal to that of the image-side meniscus.

Furthermore, according to still another feature of this invention, the distance of the confronting inner vertices of these menisci (i.e. the length of the diaphragm space) should be less than of the overall focal length 1 while the thickness of these menisci is so chosen that their outer vertices, i.e. those facing away from the diaphragm space, are separated by a distance ranging between 0.37 and 0.6 This arrangement affords a compact construction with good flattening of the image field. I

The forward meniscus, preceded by a strongly collective lens member, serves mainly to concentrate the incident light rays near the axis of the system in the region of the diaphragm which it does by virtue of the fact that its forward surface is distinctly convex and that its own axial thickness lies between about one-third and one-half of the aforementioned distance between the outer vertices,

this thickness being always greater than the width of the diaphragm space.

Still another feature of the invention, designed to suppress chromatic aberrations, resides in the construction of at least one meniscus adjacent the diaphragm space as a doublet composed of two constituent lenses of opposite refractivity whose dispersion constants or Ab-b numbers 0 are so chosen that the intervening cemented surface overcorrects for longitudinal chromatic aberrations. More particularly, this cemented surface should be negatively retracting and the constituent lens of higher refractive index (preferably a biconcave element adjoining the diaphragm space) should have the lower 1! value.

The invention will be described hereinafter with greater detail, reference being made to the accompanying drawing in which:

FIG. 1 illustrates, in conventional sectional representation, a simple objective system embodying the invention with a negative front component comprising a single lens member;

FIG. 2 is a view similar to FIG. 1, showing a modified system with two air-spaced lens members constituting the negative front component;

FIG. 3 is another view similar to FIG. 1, showing a system with a three-member negative front component; and

FIGS. la, 2a and 3a are diagrammatic views of the system of FIGS. 1, 2 and 3, respectively, identifying certain common parameters of these systems.

In FIG. 1 I have shown an objective system according to my invention, consisting of a negatively retracting front component F and a positively retracting rear component R. Component F, in this embodiment, is represented by a single dispersive lens member I in the form of a negative meniscus Ll with radii r r and thickness d,. Component R, separated from component F by an air space d consists of four members II, III, IV and V. These members are, respectively, a positive lens L2 (radii r r thickness d 21 meniscus-shaped singlet L3 (radii r r thickness 11,-) of low refractive power (here negative) following the lens L2 with a spacing 11,; and adjoining a diaphragm space d a meniscus-shaped doublet of low collective power composed of a biconcave lens L4 (radii r r thickness d-;) and a biconvex lens L5 (radii r r thickness d on the image side of the diaphragm space ci and a positive rear lens L6 (radii rm, r

thickness d separated from lens member IV by an air space :1

Representative values of the parameters of the system of FIG. 1, for an objective with an aperture ratio of 112.8,

a field angle of 63 and a back-focal length of 105.2 units (e.g. millimeters) based upon an overall focal length f of 100 units, are given in the following Table I. These parameters include the radii of curvature r -r the thicknesses and separations d d and the refractive indices n and Abb numbers w based upon the E-line of the spectrum.

TABLE I Thick- Component Member Lens Radii nesses and n. w

separations 11 67.56 F- I L1 d1 5. 62 1. 47236 67.10 m 35. 23

d; =16. 87 Air space m =954. 17 II L2 d3 =16. 59 1. 69660 53.18

' d4 7.03 Air pace r5 43. 89 III L3 d5 =16. 87 1. 74793 44. 65

do =11. Diaphragm space R n 59.18

L4 d7 25 1.62410 36.10 IV n; 51 90 d 0.28 Air space T10=-478. 21 V L6 d1o= 7.03 1.69400 54. 60

Total 96. 44

In FIG. 2 I show an alternate embodiment whose front component F is composed of two air-spaced lens members I, II, respectively represented by a positive singlet L1 (radii r r and thickness d and a negative meniscus L2 (radii r r thickness d with intervening air space d A large intercomponent air space d separates lens member II from the first member III of the associated rear component R, the member III being similar to member II of FIG. 1 and consisting of a posi (radii r r thickness d following the doublet V' with a separation d Representative values of the parameters r .r d -d n and w of the system of FIG. 2, defining an objective of an aperture ratio of 1:4, a field angle of and a back-focal length of 113.4 units (based upon an overall focal length f=l00), are listed in the following Table II.

TABLE II Thick- Component Member Lens Radii nesses and n v.

separations 1' L1 al =15. 70 1.62287 60.06

=00 F dz 0.35 Air Space r3 =+313. 89 II L2 d1 6.28 1.51871 l 63.06

d =40. 47 Air space r5 =+378. 93 III L3... (1 =17. 44 1. 70586 40.87

d6 0.35 Airspace 1 54.12 1V L4 d1 =17. 79 1. 70189 38. 38

ds' 9. 42 Diaphragm space R n 94.38

L5 119' 2.79 1. 70442 34.67 V. T1u 44. 80

L6 din =12. 21 1. 62287 60. 06

1 (J 35 Air space m 302. 86 V1 L7 dw= 6.98 1. 69660 53.18 t m'=- 80. 32

Total 130. 13

FIG. 3 illustrates a further embodiment whose front component F is composed of three air-spaced members I", II" and HI" respectively constituted by a first negative meniscus L1" (radii r r and thickness d a biconvex singlet L2 (radii r r thickness d and a second negative meniscus L3" (radii r r thickness d the intervening air spaces having been designated d b and d Separated from component F" by a large air space d is a four-member rear component R whose members have been designated IV", V", VI" and VII. It will be noted that the first member IV" and the last member VII", respectively reprethe length I; of the diaphragm space d d or 21 containing the diaphragm D, the distance 1 between the vertices of the convex outer surfaces r r or r and r r or r of the two confronting menisci, the radius TA of the concave surfaces r r or r of the first meniscus, the radius r of the concave surfaces r r or r of the second meniscus, and the back-focal length s. These parameters or their ratios have been summarized for comparison, along with the individual focal length of the front component and the individual focal length f of the rear meniscus IV, V or VI", in terms of the overall focal length 1 in the following Table IV.

sented by -a positive singlet L4 (radii r r thickness d and by another positive singlet L8" (radii r r thickness al are generally similar to the corresponding members R and R in FIGS. 1 and 2 but that, in contradistinction to these two preceding embodiments, the second member V of component R" is now a doublet, constituted by a biconvex lens L5" (radii r r thickness d and a .biconcave lens L6" (radii r r thickness d whereas the third member VI is a positive singlet L7'T (radii r r thickness dlg") separated from member V" by the diaphragm space d The spaces intervening between members I and V" and between VI" and VII" have 1 been respectively designated d l and (1 Representative parameters of the system of FIG. 3, constituting an objective with a relative aperture of 1:2.8, a field angle of 80 and a back-focal length of 146.58 units (with overall length 1: 100), i.e. the radii ni -r the thicknesses and separations dp -du" and the associated refractive indices n and Abb numbers w are given in the following Table III.

It will be noted that the first and fourth members of the rear component in each of the specifically disclosed systems are strongly collective, as compared with the interposed meniscus-shaped member, the individual focal length of each of these collective members being less than twice the overall focal length 1 of the system.

I claim: 1

1. An optical objective system composed of a negatively refracting front component and a positively refracting rear component air-spaced from said front component, said rear component consisting of four air-spaced lens members including a strongly collective first member, a meniscus-shaped second member of low refractive power having a convex front surface and a concave rear surface, a meniscus-shaped collective third member having a concave front surface and a convex rear surface, said concave surfaces encompassing a diaphragm space, and a strongly collective fourth member, said front component being singlet, said third member being a doublet, the numerical values of the radii r or r and the thicknesses and separations a' to d of said singlet Ll, said first member L2.

TABLE III Thick- Component Member Lens Radii nesses and n, v,

separations 1," =+266. 77 I L1' dw 9.81 1. 61871 63. 96

(12" =31. 38 Air space r =+286. 39 F II L2'-.... d3 =23. 54 1. 72823 37. 81

d4" 0. 39 Air space r5" =+430. 21 III' L3' d 7. 58 1. 62287 60. 06

do =76. Air space n =+129.1I IV'. L4"-.- d1" =23. 54 1. 74703 27. 82

2, Air space T 67. 32 L5'...... dw =15. 69 1. 55440 63. 22 V' Tm"=--120. 52

m"=-I- 62. 14 R d11"=11. 77 Diaphragm space r -=-127. 78 VI'.... L7'.... dw'= 9. 81 1. 62287 60. 06

d1a"= 0. 39 Air space T14"=+366. 69 VII' L8'..- d14"= 9. 81 1. 62287 60. 06

7'1 -144. 88 Total (1.... 236. 96

In FIGS. 1a, 2a and 3a I have indicated certain common parameters of the three systems described above, i.e.

said second member L3, the constituent lenses L4 and L5 of said third member, and said fourth member L6, based the length l of the intercomponent space d dr or d 75 upon an overall focal length of numerical value 100, and

of their refractive indices n,, and dispersion constants w being substantially as given in the following table:

Thicknessess Member Lens Radii and no ve separations r1 67. 56 I L1 d1= 5.62 1.47236 67.10

d2 =16. 87 Air space rs =954 17 II L2 da =16. 59 1.69660 53.18

d. 7.03 Air space r5 43 89 III L3 d5 =16. 87 1. 74703 44. 65

d =11. 25 Diaphragm space f7 59. 18 1.4-..- d1 2.25 1.62410 36.10 IV r 51 90 L5.... (is =12. 65 1. 62287 60. 06

d; 0.28 Air space Tio= ---478 21 V L6.... dw= 7.03 1.69400 54.60

2. An optical objective system composed of a negatively refracting front component and a positively re-- fracting rear component air-spaced from said front component, said rear component consisting of four air-spaced lens members including a strongly collective first member, a meniscus-shaped second member of low refractive power having a convex front surface and a concave rear surface, a meniscus-shaped collective third memher having a concave front surface and a convex rear surface, said concave surfaces encompassing a diaphragm space, and a strongly collective fourth member, said front component consisting of a positive first lens and a negative second lens air spaced from said first lens, said third member being a doublet, the numerical values of the radii r to r and the thicknesses and separations d to a of said first lens L1, said second lens L2, said first member L3, said second member L4, the constituent lenses L5 and L6 of said third member, and the fourth member L7, based upon an overall focal length of numerical value 100, and of their refractive indices n and dispersion constants w being substantially as given in the following table:

Thicknesses Member Lens Radii and n, v.

separations r =+209. 46 I L1... 61' =15. 70 1.62287 6006 d2 0.35 Air space 1 =+313.89 II L2.-- d3 6.28 1.51871 63.96

d. =40. 47 Air space r =+378 93 III. L3. ds' =17. 44 1. 70586 40. 87

d8 0.35 Air space r 54.12 IV L4... dz =17. 79 1.70189 38.38

d3 9.42 Diaphragm space 1 94.38 L5 dw 2. 79 1. 70442 34. 67 V 7'1u'=+ 44.80

L6. dio'=l2. 21 1. 62287 60.06

dn'= 0.35 Air space m'=302 86 VI L7... d1t'= 6.98 1.69660 53.18

Tia'= 80.32

3. An optical objective system composed of a negatively refracting front component and a positively refracting rear component air-spaced from said front component, said rear component consisting of four air-spaced lens members including a strongly collective first memher, a meniscus-shaped second member of low refractive power having a convex front surface and a concave rear surface, a meniscus-shaped collective third member having a concave front surface and a convex rear surface, said concave surfaces encompassing a diaphragm space, and a strongly collective fourth member, said front component consisting of a negative first lens, a positive second lens and a negative third lens air-spaced from one another, said second member being a doublet, the numerical values of the radii r to r and the thicknesses and separations d to d of said first lens L1", said second lens L2", said third lens L3", said first member L the constituent lenses :LS" and L6" of said second member, said third member L7", and said fourth member L8", based upon an overall focal length of numerical value 100, and of their refractive indices n and dispersion constants w being substantially as given in the following table:

Thicknesses Member Lens Radii and n. v.

separations n" 266.77 I L1... d1 9.81 1.51871 63.96

dz" =31. 38 Air .pace r3" 286. 39 II L2. d =23. 54 1. 72823 37.81

d4" 0.39 Air .pace r 430.21 III'.. L3... is" 7.85 1.62287 60.06

d =76. Air space 1 129.11 IV- L4- d1" =23. 54 1. 74703 27. 82

Tall :00

d 2.75 Air space 1n" 67.32 L5'. d =15. 69 1. 55440 63. 22 V' T o"= 120. 52

L6-.- d1u"=13. 73 1. 72732 29. 07

Tun=+ 62.14

dil"=11. 77 Diaphragm space nz"= 127.78 VI'. L7-.- d z"= 9.81 1.62287 60.06

dn"= 0.39 Air pace T14"=+ 366. 69 VII. L8..- diw= 9. 81 1. 62287 60.06

References Cited UNITED STATES PATENTS 2,649,022 8/ 1953 Angemeux 350-216 2,696,758 12/ 1954 Angemeux 350-215 2,793,565 5/ 1957 Zollner 350-216 FOREIGN PATENTS 931,063 7/1963 Great Britain. 1,192,221 4/1959 France.

DAVID SCHONBERG, Primary Examiner.

R. J. ST-ERN, Assistant Examiner. 

